联二萘酚类磷酸吡哆醛模拟酶的合成与应用研究进展

模拟酶化合物的合成与应用研究具有重要的理论和实际意义。近年来研究的一些联二萘酚类磷酸吡哆醛模拟酶具有氨基酸构型转换的功能,并可用于手性氨基醇的对映选择性识别。本文简要介绍了该类化合物的合成方法,综述了近年来联二萘酚类磷酸吡哆醛模拟酶在手性氨基酸构型转换、手性氨基醇对映选择性识别以及萃取拆分等方面的应用。     

Catalytic activity of carbon nanotubes in the conversion of aliphatic alcohols

Carbon nanotubes (CNTs) obtained via the catalytic pyrolysis of hexane at 750°C were studied as the catalysts in conversion of C₂–C₄ alcohols. The efficiency of CNTs as catalysts in dehydration and dehydrogenation of ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and tert-butanol was studied by means of pulse microcatalysis. The surface and structural characteristics of CNTs are investigated via SEM, TEM, DTA, BET, and XPS. CNTs are shown to be effective catalysts in the conversion of alcohols and do not require additional oxidative treatment. The regularities of the conversion of aliphatic alcohols, related to the properties of the CNTs surface and the structure of the alcohols are identified.     

Oxone/Sodium Chloride: A Simple and Efficient Catalytic System for the Oxidation of Alcohols to Symmetric Esters and Ketones

An efficient method for the oxidation of alcohols is presented. The use of catalytic amounts of sodium chloride in combination with oxone allows the conversion primary aliphatic alcohols to symmetric esters. Secondary alcohols can be easily oxidized to ketones, and benzylic alcohols are converted to the corresponding aldehydes. The method is cost effective and enviromentally benign.     

Barium dichromate [BaCr2O7], a mild reagent for oxidation of alcohols to their corresponding carbonyls in non-aqueous polar aprotic media

Barium dichromate is used as a mild oxidizing agent for the selective conversion of primary and secondary alcohols to their corresponding aldehydes and ketones, respectively. Over-oxidation does not occur and primary alcohols undergo oxidation to the aldehyde. Primary and secondary benzylic alcohols are oxidized faster and more efficiently.     

Asymmetric synthesis of highly substituted beta-nitro alcohols and enantiomerically enriched 4,4,5-trisubstituted oxazolidinones

It is demonstrated that alpha,alpha-disubstituted-alpha-nitroketones are reduced to the corresponding trisubstituted nitro alcohols in good to excellent yield and enantiomeric excess by borane-dimethyl sulfide in the presence of a chiral oxazaborolidine catalyst. Reduction of the nitro alcohols to the corresponding amino alcohols and their subsequent conversion to enantiomerically enriched 4,4,5-trisubstituted oxazoldinones is also reported.     

Solvent‐Free Conversion of Alcohols into Iodides with NaI Supported on KSF Clay

A variety of allylic, benzylic, primary, and secondary saturated alcohols have been converted into the corresponding iodides using NaI supported on KSF clay. Selective conversion of allylic and benzylic alcohols in the presence of primary and secondary saturated alcohols has also been demonstrated.     

Isothiourea-Catalyzed Acylative Kinetic Resolution of Tertiary α-Hydroxy Esters

A highly enantioselective isothiourea-catalyzed acylative kinetic resolution (KR) of acyclic tertiary alcohols has been developed. Selectivity factors of up to 200 were achieved for the KR of tertiary alcohols bearing an adjacent ester substituent, with both reaction conversion and enantioselectivity found to be sensitive to the steric and electronic environment at the stereogenic tertiary carbinol centre. For more sterically congested alcohols, the use of a recently-developed isoselenourea catalyst was optimal, with equivalent enantioselectivity but higher conversion achieved in comparison to the isothiourea HyperBTM. Diastereomeric acylation transition state models are proposed to rationalize the origins of enantiodiscrimination in this process. This KR procedure was also translated to a continuous-flow process using a polymer-supported variant of the catalyst.     

Catalytic conversion of aliphatic alcohols on carbon nanomaterials: The roles of structure and surface functional groups

Carbon nanomaterials with the structure of graphene and different compositions of the surface groups are used as catalysts for the conversion of С₂–С₄ aliphatic alcohols. The conversions of ethanol, propanol- 1, propanol-2, butanol-1, butanol-2, and tert-butanol on carbon nanotubes, nanoflakes, and nanoflakes doped with nitrogen are investigated. Oxidized and nonoxidized multiwalled carbon nanotubes, nanoflakes, and nanoflakes doped with nitrogen are synthesized. X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning and transmission electronic microscopies, Brunauer–Emmett–Teller method, derivatographic analyses, and the pulsed microcatalytic method are used to characterize comprehensively the prepared catalysts. It was established that all of the investigated carbon nanomaterials (with the exception of nondoped carbon nanoflakes) are bifunctional catalysts for the conversion of aliphatic alcohols, and promote dehydration reactions with the formation of olefins and dehydrogenation reactions with the formation of aldehydes or ketones. Nanoflakes doped with nitrogen are inert with respect to secondary alcohols and tert-butanol. The role of oxygen-containing and nitrogen-containing surface groups, and of the geometrical structure of the carbon matrix of graphene nanocarbon materials in the catalytic conversion of aliphatic alcohols, is revealed. Characteristics of the conversion of aliphatic alcohols that are associated with their structure are identified.     

Isothiourea‐Catalyzed Acylative Kinetic Resolution of Tertiary α‐Hydroxy Esters

A highly enantioselective isothiourea‐catalyzed acylative kinetic resolution (KR) of acyclic tertiary alcohols has been developed. Selectivity factors of up to 200 were achieved for the KR of tertiary alcohols bearing an adjacent ester substituent, with both reaction conversion and enantioselectivity found to be sensitive to the steric and electronic environment at the stereogenic tertiary carbinol centre. For more sterically congested alcohols, the use of a recently‐developed isoselenourea catalyst was optimal, with equivalent enantioselectivity but higher conversion achieved in comparison to the isothiourea HyperBTM. Diastereomeric acylation transition state models are proposed to rationalize the origins of enantiodiscrimination in this process. This KR procedure was also translated to a continuous‐flow process using a polymer‐supported variant of the catalyst.     

Sodium iodide/boron trifluoride etherate: A mild reagent system for the conversion of allylic and benzylic alcohols into corresponding iodides and sulfoxides into sulfides

A variety of allylic and benzylic alcohols have been converted into the corresponding iodides using NaI/BF₃.Et₂O. Selective conversion of allylic and benzylic alcohols in preference to primary saturated alcohols has also been demonstrated. Further, the same reagent system has been used to convert sulfoxides into sulfides under mild conditions.     

Direct Arylation/Alkylation/Magnesiation of Benzyl Alcohols in the Presence of Grignard Reagents via Ni-, Fe-, or Co-Catalyzed sp(3) C-O Bond Activation

Direct application of benzyl alcohols (or their magnesium salts) as electrophiles in various reactions with Grignard reagents has been developed via transition metal-catalyzed sp(3) C-O bond activation. Ni complex was found to be an efficient catalyst for the first direct cross coupling of benzyl alcohols with aryl/alkyl Grignard reagents, while Fe, Co, or Ni catalysts could promote the unprecedented conversion of benzyl alcohols to benzyl Grignard reagents in the presence of (n)hexylMgCl. These methods offer straightforward pathways to transform benzyl alcohols into a variety of functionalities.     

用芹菜茎催化对映选择性还原芳香酮

研究了用芹菜茎薄片在温和与环境友好的条件下催化芳香酮的对映选择性还原反应, 制备得到具有光学活性的(S)-1-芳基醇, 产物的对映选择性符合Prelog规则. 考察了pH值、反应时间、反应温度、底物浓度等因素对底物芳香酮的转化率和产物(S)-1-芳基醇的对映体过量值的影响, 并优化了这些反应条件. 文中还研究了底物的构效关系, 发现羰基两边取代基的空间效应和电子效应明显影响底物的转化率和产物的对映体过量值. 在合适的条件下底物苯乙酮的转化率高达100%, 产物(S)-1-苯基乙醇的对映体过量值大于99.0%. 苯丙酮、对甲基苯乙酮和对氯苯乙酮等其它芳香酮的转化率达到中等程度, 但所得(S)-1-芳基醇的最大对映体过量值均大于99.0%.     

Sulfuric Acid Adsorbed on Silica Gel. A Multipurpose Acid Catalyst

A series of acid catalyzed reactions like the dehydration of alcohols, conversion of ketones to 1,3-dioxolanes and their hydrolysis, α,β-unsaturated ketones to enol ethers, and alcohols to methyl-methoxyethyl ethers are performed efficiently in high yield with sulfuric acid adsorbed on silica gel as catalyst.     

A CONVENIENT ONE-POT METHOD OF CONVERTING ALCOHOLS INTO OXIMES

The one-pot conversion of[3pc] primary and secondary alcohols into oximes is reported using chromium trioxide supported on alumina and hydroxylamine hydrochloride under solvent free condition. This oxidation-oxime formation reaction has been applied to a range of aliphatic and benzylic alcohols.     

Synthesis of imines from nitrobenzene and TiO2 particles suspended in alcohols via semiconductor photocatalysis type B

UV irradiation on a non-aqueous suspension of titanium dioxide with nitrobenzene and different alcohols in deaerated conditions produces imines and aniline as main products. The conversion of nitrobenzene and the corresponding selectivity of imines or aniline depend on the type of alcohol used. A low conversion (3-12%) and selectivity close to 100% to imines were obtained with methyl, ethyl, or propyl alcohol. Otherwise, using i-propanol only aniline was detected with a conversion of 13%. Finally, a mixture of aniline and imines was formed employing n-butyl, n-amyl, and i-amyl alcohols with the higher conversion (∼50%).     

DMSO-catalyzed chlorination of alcohols using N-phenylbenzimidoyl chloride

N-phenylbenzimidoyl chloride has been demonstrated as an efficient chlorination reagent catalyzed by dimethyl sulfoxide (DMSO) in conversion of alcohols to corresponding chlorides. The reaction conditions were mild, and most of the substrates gave satisfactory yields. The configuration inversion of the chlorination was proved using optically active phenyl alcohols. The amount of DMSO can be as low as 0.001 eq without reducing the efficiency of the chlorination. A plausible mechanism for the reaction was proposed and proved by experiments. The reaction is stereoselective and potentially chemoselective among primary benzyl alcohols, secondary benzyl alcohols, and unactivated aliphatic alcohols.     

A one-pot oxidation/allylation/oxidation sequence for the preparation of β,γ-unsaturated ketones directly from primary alcohols

A one-pot oxidation/allylation/oxidation procedure has been developed for the conversion of primary alcohols into β,γ-unsaturated ketones. The methodology has been applied to a range of alcohols, and in some cases, isomerisation to produce the corresponding α,β-unsaturated ketones has been carried out.     

In situ oxidation-imine formation-reduction routes from alcohols to amines

Manganese dioxide is employed as an in situ oxidant for the one-pot conversion of alcohols into imines. In combination with polymer-supported cyanoborohydride (PSCBH), a one-pot oxidation-imine formation-reduction sequence is reported. This procedure enables alcohols to be converted directly into both secondary and tertiary amines.     

Advances in direct production of value-added chemicals via syngas conversion

Syngas conversion to fuels and chemicals is one of the most challenging subjects in the field of C1 chemistry. It is considered as an attractive alternative non-petroleum-based production route. The direct synthesis of olefins and alcohols as high value-added chemicals from syngas has drawn particular attention due to its process simplicity, low energy consumption and clean utilization of carbon resource, which conforms to the principles of green carbon science. This review describes the recent advances for the direct production of lower olefins and higher alcohols via syngas conversion. Recent progress in the development of new catalyst systems for enhanced catalytic performance is highlighted. We also give recommendations regarding major challenges for further research in syngas conversion to various chemicals.     

1,2-bis(diphenylphosphino)ethane tetrahalide: A convenient reagent for the conversion of alcohols to the corresponding halides

Efficient and rapid conversion under mild conditions of various alcohols and tetrahydro-2-pyranyl (THP) protected alcohols into the corresponding halide (Br or I) are described using the corresponding 1,2-bis (triphenylphosphino)ethane tetrahalide. Tert-butyldimethylsilyl ethers, esters and olefins are stable to these conditions.